We propose to carry out, for the first time, a comprehensive longitudinal survey of new legal immigrants to the United States based on nationally representative samples of the administrative records of immigrants newly admitted to permanent residence. We recently completed a successful baseline round, NIS-2003-1, interviewing 8,573 sampled adult immigrants, 810 sponsor-parents of sampled child immigrants, and spouses of both groups, and assessing their children. We propose here a follow-up round that will re- interview baseline respondents and their spouses and assess their children. The results obtained from the baseline have informed all elements of the design for the second round, NIS-2003-2. To monitor adaptation over time, our baseline sample must be interviewed at regular intervals over the life cycle. To assess the immigrants'legacy, information is also obtained about and from their children, both the immigrant children they brought with them and the U.S. citizen children born to them in the United States. We are also putting into the public domain a public-use data base from these surveys that will provide an important source of information to assess U.S. immigration laws, the assimilation and experiences of immigrants, and the impact of immigration in the United States. These data provide prospective and retrospective information of pre-immigration education, work, health, migration, marriage and fertility histories for newly-arrived immigrants. They also provide useful information on health, on economic status, on schooling, and on children's well-being from a population heterogeneous in English language abilities and native languages. Demographic trends suggest that the health status of immigrants and their descendants will play an increasingly central role in shaping health outcomes of the American people. Identifying the determinants of the original health selection of migrants and the forces that shape health paths following immigration is critical to understanding ethnic health differences. The NIS will put into the public-domain data that can be used to follow the health trajectories of new immigrants.